JPH11116794A - Resin composition for IC tray molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyphenylene ether resin and a polystyrene resin having a syndiotactic structure by mixing conductive particles and conductive fibers to lower the surface resistance of a molded product and to impart conductivity by lowering the surface resistance. A resin composition for molding an IC tray with low heat resistance and high fluidity, which can be molded at a relatively low temperature, thereby suppressing generation of gas at the time of molding and having low mold contamination. SOLUTION: (a) The weight ratio of polyphenylene ether to polystyrene having a syndiotactic structure is 99.
100 parts by weight of a mixture having an oil absorption of at least 70 ml / 100 g or a volume resistivity of 10E0 Ω · c.
5 to 35 parts by weight of at least one selected from carbon fibers having a molecular weight of m or less; and (c) 0 to 30 parts by weight of polystyrene having no syndiotactic structure;
(D) 0 to 50 parts by weight of rubber-like substance, (e) 0 to 20 parts by weight of polyolefin resin, (f) non-conductive inorganic filler 0
A resin composition for molding an IC tray, comprising from 30 to 30 parts by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for molding an IC tray which is excellent in antistatic properties or conductivity, workability and heat resistance and has low mold contamination during molding.

[0002]

2. Description of the Related Art Polyphenylene ether resins are thermoplastic resins having excellent properties such as mechanical properties, heat resistance and dimensional stability. However, polyphenylene ether resin alone has remarkably poor impact properties and solvent resistance, and also has poor meltability due to its high melt viscosity. Therefore, a polystyrene resin compatible with the polyphenylene ether resin is added to improve the fluidity. However, when a large amount of the polystyrene resin is added, the heat resistance is significantly reduced. Investigations have also been made to improve the fluidity by mixing a fluidity improver, but there are many problems such as generation of gas during injection molding and mold contamination. In particular, the injection molding temperature of the polyphenylene ether resin composition having high heat resistance is generally very high, such as 300 ° C. to 350 ° C., so that a large amount of gas is generated at the time of molding due to decomposition products and volatile components of the resin. When this gas is used for continuous molding, mold contamination is remarkable and there is a serious problem in practical use. In addition, since many of the polyphenylene ether resin compositions are non-conductive, when used as an IC tray as in the present application, conductive particles,
Flakes and fibers, particularly conductive carbon black and carbon fibers, are mixed to impart conductivity.
In the field of electricity and electronics, ICs with high heat resistance, dimensional stability, antistatic properties and conductivity, and excellent productivity
Tray development requirements have recently increased.

[0003]

The object of the present invention is to reduce the surface resistance of a molded product by mixing conductive particles and conductive fibers into a polyphenylene ether resin and a polystyrene resin having a syndiotactic structure. To provide a resin composition having high heat resistance, high fluidity, and low mold contamination.

[0004]

Means for Solving the Problems The present inventors mixed conductive particles and conductive fibers into a polyphenylene ether resin and a polystyrene resin having a syndiotactic structure to lower the surface resistance of a molded article and to impart conductivity. By doing so, it has been considered that molding with high productivity can be performed by a resin composition having high heat resistance, high fluidity, and low mold contamination due to holding down the molding temperature.

That is, the present invention relates to a mixture (a) comprising a mixture of polyphenylene ether and polystyrene having a syndiotactic structure in a weight ratio of 99/1 to 10/90.
0 parts by weight, (b) dibutyl phthalate oil absorption 70 ml
5 to 35 parts by weight of at least one selected from the group consisting of carbon black having a volume of 100 g or more and carbon fiber having a volume resistance of 10E0 Ω · cm or less, and (c) 0 to 30 parts by weight of a polystyrene having no syndiotactic structure. Parts, (d) 0 to 50 parts by weight of a rubber-like substance,
The present invention relates to a resin composition for molding IC trays, comprising (e) 0 to 20 parts by weight of a polyolefin resin and (f) 0 to 30 parts by weight of a non-conductive inorganic filler.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The component (a) polyphenylene ether used in the present invention is represented by the following general formula (wherein R ₁ ,
R ₂ , R ₃ , R ₄ and R ₅ are selected from hydrogen, halogen atom, hydrocarbon group or substituted hydrocarbon group,
One of them is always a hydrogen atom. ) Is a polymer obtained by oxidatively polymerizing one or more of the phenol compounds represented by the formula (1) with oxygen or an oxygen-containing gas using an oxidation coupling catalyst.

Specific examples of R ₁ , R ₂ , R ₃ , R ₄ and R _{5 in} the above general formula include hydrogen, chlorine, bromine, fluorine, iodine, methyl, ethyl, n- or iso-propyl, pri-, sec- or t-butyl, chloroethyl, hydroxyethyl, phenylethyl, benzyl,
Examples include hydroxymethyl, carboxyethyl, methoxycarbonylethyl, cyanoethyl, phenyl, chlorophenyl, methylphenyl, dimethylphenyl, ethylphenyl, allyl and the like.

Specific examples of the above general formula include phenol, o-, m- or p-cresol, 2,6-,
2,5-, 2,4- or 3,5-dimethylphenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2,6-diethylphenol,
-Methyl-6-ethylphenol, 2,3,5-, 2
3,6- or 2,4,6-trimethylphenol, 3
-Methyl-6-t-butylphenol, thymol, 2-
Methyl-6-allylphenol and the like.

Further, phenol compounds other than the above general formula, for example, polyhydric hydroxyaromatic compounds such as bisphenol-A, tetrabromobisphenol-A, resorcinol, hydroquinone and novolak resin, and phenol compounds represented by the above general formula Is also good. Among these compounds, preferred are a homopolymer of 2,6-dimethylphenol or 2,6-diphenylphenol and a large amount of 2,6-xylenol and a small amount of 3-methyl-6-t-t-. Copolymers of butylphenol or 2,3,6-trimethylphenol are exemplified. The oxidative coupling catalyst used for oxidative polymerization of the phenol compound is not particularly limited, and any catalyst having a polymerization ability can be used.

Further, the polyphenylene ether in the present invention includes those obtained by grafting a styrene compound to the above-mentioned polyphenylene ether or those obtained by grafting another polymer. Examples of the styrene-based compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, and chlorostyrene.

The preferable range of the molecular weight of the polyphenylene ether is 0.3 to 0.7 as a measure of the intrinsic viscosity measured using 25 ° C. chloroform.
5 dl / g, preferably 0.35 to 0.5 dl / g
g, more preferably 0.35 to 0.48 dl /
g. If the value is smaller than this, the mechanical strength of the composition is low. On the other hand, if the value is larger than this, molding processability of the composition is undesirably reduced.

The polystyrene having a syndiotactic structure of the component (a) refers to a syndiotactic structure whose stereochemical structure is mainly a phenyl group or a substituted phenyl group which is a side chain to a main chain formed from carbon-carbon bonds. A phenyl group has a steric structure in which phenyl groups are alternately located in opposite directions, and its tacticity is quantified by nuclear magnetic resonance ( ^13C -NMR) using isotope carbon. ¹³
The tacticity measured by the C-NMR method can be represented by the abundance ratio of a plurality of continuous structural units, for example, dyad for two, triad for three, and pentad for five. The polystyrene having a syndiotactic structure referred to in the present invention is generally a polystyrene having a syndiotacticity of 85% or more in a dyad or 35% or more in a pentad (racemic pentad), preferably 50% or more. Alkylstyrene), poly (halogenated styrene),
Poly (alkoxystyrene), poly (benzoic acid ester styrene) and mixtures thereof, or copolymers containing these as main components are referred to. The poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene) and the like, and poly (halogenated styrene) includes Examples include poly (chlorostyrene) and poly (bromostyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

Further, polystyrene having the syndiotactic structure (hereinafter sometimes simply referred to as SPS)
The molecular weight and molecular weight distribution are not particularly limited, but those having a molecular weight of 30,000 or more, preferably 50 to 2,000,000 are used. Further, it is desirable that the amount of the remaining styrene monomer is 5000 ppm or less. The styrene-based polymer has a melting point of 260 to 270 ° C., and is much more excellent in heat resistance and solvent resistance than a conventional styrene-based polymer having an atactic structure. In the present invention, the SPS of the component (a) may be used alone or in combination of two or more.

The mixing ratio of polyphenylene ether to polystyrene having a syndiotactic structure is from 99/1 to 10/90 by weight. The preferred range of the weight ratio is from 95/5 to 15/85, more preferably from 90/10 to 20/80. If the ratio of polyphenylene ether is lower than this, the processability of the composition is improved, but the molded product is significantly deformed, which is not preferable.

The carbon black of the component (b) used in the present invention refers to carbon black used for coloring, reinforcing rubber, and imparting conductivity. However, in order to efficiently impart conductivity to the amount of carbon black added,
Dibutyl phthalate oil absorption of carbon black is 70m
It is necessary to be 1/100 g or more. The term “dibutyl phthalate oil absorption” as used herein means ASTM D2414.
It is a value measured by the method specified in. A preferable dibutyl phthalate oil absorption is 100 ml / 100 g or more and 60 ml or more.
0 ml / 100 g or less. More preferred oil absorption of dibutyl terephthalate is 150 ml / 100 g or more.
It is 50 ml / 100 g or less. Particularly preferred carbon blacks include, for example, acetylene black obtained by thermally decomposing acetylene gas, and Ketjen black produced by furnace type incomplete combustion using crude oil as a raw material. The conductivity of these carbon blacks can be efficiently improved by adding a small amount thereof.

The carbon fiber of the component (b) used in the present invention refers to a carbon fiber used for reinforcing a resin or imparting conductivity. However, in order to efficiently impart conductivity to the amount of carbon fiber added, the volume resistance of the carbon fiber needs to be 10E0 Ω · cm or less. The preferred volume resistance is 10E-
A more preferred volume resistance of 1 Ω · cm or less is 10
E−2 Ω · cm or less.

There are no particular restrictions on the material and shape of the carbon fiber, but chopped fibers such as commonly used pan-based carbon fibers or pitch-based carbon fibers are preferred. There is no particular rule for the sizing agent and the like.

The amount of carbon black or carbon fiber added is based on 100 parts by weight of component (a).
It is 5 to 35 parts by weight, preferably 5 to 33 parts by weight, particularly preferably 8 to 30 parts by weight. If the addition amount is less than 5 parts by weight, the antistatic property and conductivity of the composition are not sufficient, and if it exceeds 35 parts by weight, the processability during kneading of the composition is reduced and the kneading cannot be performed uniformly.

As the component (c), polystyrene having no syndiotactic structure may be used. Styrene-based resins are specifically styrene, α-methylstyrene,
A polymer consisting of one or more polymer units selected from p-methylstyrene and the like, specifically, polystyrene, rubber-reinforced polystyrene, poly α-methylstyrene,
Poly p-methylstyrene, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer and the like can be mentioned.

In the present invention, a rubber-like substance (d) may be used to improve the impact strength. Rubber-like substances refer to natural and synthetic polymeric materials that are elastic at room temperature. Particularly preferred rubbers include ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene copolymer rubber, ethylene-butene-1 copolymer rubber, polybutadiene, styrene-butadiene block copolymer rubber,
Styrene-butadiene copolymer rubber, partially hydrogenated styrene
Butadiene-styrene block copolymer rubber, styrene-
Isoprene block copolymer rubber, partially hydrogenated styrene-isoprene block copolymer rubber, polyurethane rubber, styrene graft-ethylene-propylene-non-conjugated diene copolymer rubber, styrene-graft-ethylene-propylene copolymer rubber, styrene / acrylonitrile-graft −
Ethylene-propylene-non-conjugated diene copolymer rubber, styrene / acrylonitrile-graft-ethylene-propylene copolymer rubber, styrene / methyl methacrylate-
Graft-ethylene-propylene-non-conjugated diene copolymer rubber, styrene / methyl methacrylate-graft-
Ethylene-propylene copolymer rubber or the like, or a mixture thereof is used. Further, a modified rubber modified with a functional monomer containing another acid or epoxy may be used. The amount of the rubber-like substance to be added is as follows: component (a) 10
0 to 50 parts by weight, preferably 2 to 48 parts by weight per 0 parts by weight
It is in the range of parts by weight. If it exceeds 50 parts by weight, heat resistance and workability will be reduced.

In the present invention, a polyolefin resin (f) may be added to the resin composition in order to improve processability. Suitable polyolefin resins include, for example, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, and poly (4-methylpentene-1). Among them, low density polyethylene and linear low density polyethylene are particularly preferred. The addition amount of the polyolefin resin is in the range of 0 to 20 parts by weight, preferably 1 to 15 parts by weight based on 100 parts by weight of the component (a). If the amount exceeds 20 parts by weight, workability is improved, but a problem of delamination occurs near the gate of the molded product, which is not preferable.

Further, in the present invention, a non-conductive inorganic filler (g) may be added to the resin composition for the purpose of improving rigidity, heat resistance or dimensional stability.

Examples of the non-conductive inorganic filler include glass fiber, silica alumina, calcium carbonate, talc,
Mica, clay, it can be used kaolin, magnesium sulfate, wollastonite, inorganic fillers such as TiO _2, ZnO and Sb ₂ O _3. The addition amount of the non-conductive inorganic filler is in the range of 0 to 30 parts by weight, preferably 1 to 25 parts by weight based on 100 parts by weight of the component (a). If it exceeds 30 parts by weight, the heat resistance is improved, but the impact resistance is lowered, which is not preferred.

Incidentally, conventional additives such as pigments, flame retardants, plasticizers, antioxidants and weathering agents may be further added to the composition of the present invention.

The resin composition for molding an IC tray of the present invention comprises:
The above components (a) and (b) or (c), (d), (e) and (f) are added to the components (a) and (b) as necessary.
Alternatively, it is obtained by adding the component (g), blending the mixture by a known method, and melt-kneading the mixture. In this case, mixing can be performed by a conventional mixing means. For this purpose, an extruder, a kneader, a roll mixer, a Banbury mixer and the like can be used.

[0026]

The present invention can be carried out by the following methods, but the present invention is not limited to these.

PPE : polyphenylene ether resin
YPX100F, SPS manufactured by Mitsubishi Gas Chemical Co., Ltd .: polystyrene having a syndiotactic structure For example, in a 2 liter reaction vessel, 1.0 liter of purified styrene and 1 mmol of triethylaluminum were added, and 80
After heating to 90 ° C., the premixed catalyst [pentamethylcyclopentadienyl titanium trimethoxide 90 micromol, dimethylanilinium tetrakis (pentafluorophenyl) borate 90 micromol, toluene 29.
1 mmol, triisobutylaluminum 1.8 mmol], 16.5 ml, and polymerization at 80 ° C. for 5 hours. SPS MSEPD : styrene / methyl methacrylate-graft-ethylene-propylene shown in Reference Example 1. -Non-conjugated diene copolymer rubber carbon black : Denka Black (acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.) (non-conductive inorganic filler) Talc : 5000S manufactured by Hayashi Chemicals

Reference Example 1 As a rubber-like substance, a styrene / methyl methacrylate-graft-ethylene-propylene-nonconjugated diene copolymer rubber was produced by the following method. 2200 ml of pure water obtained by dissolving 6 g of Pluronic F686 manufactured by Asahi Denka Co., Ltd.
300 g of Esprene E502 (44 parts by weight of propylene content, iodine value of 8.5, Mooney viscosity at 120 ° C. of 63) cut into 6 mm square was charged and stirred and suspended. Next, 9 g of t-butyl peroxypivalate and 0.18 g of P-benzoquinone as a polymerization initiator, 101 g of styrene and 101 g of methyl methacrylate each as a monomer,
19 g is added, and the autoclave is immediately placed in an oil bath which has been previously heated to 30 ° C., and the heating is started. 1
The temperature is raised to 110 ° C at a rate of about 1 ° C per minute,
The polymerization reaction was performed while maintaining the temperature at 110 ° C. for 0 minute. The resulting granular graft was washed with water, dried in vacuum at 95 ° C., and subjected to styrene / methyl methacrylate-graft-ethylene-propylene-non-conjugated diene copolymer rubber (MSEPD).
M) was obtained.

After blending each component at the following composition ratio, a twin-screw kneader (for example, TEM-50A 50 mm manufactured by Toshiba Machine Co., Ltd.)
And the mixture is melt-kneaded and pelletized. When molding IC trays by injection molding using these pellets, the same heat-resistant IC trays can be molded at a temperature about 20 ° C. lower than in the past, so that daily maintenance of the mold was conventionally required. It has been concluded that the use of the resin composition can significantly improve the productivity, about once every three days.

[0030]

[Table 1]

[0031]

As described above, according to the present invention,
By mixing conductive particles and conductive fibers into polyphenylene ether resin and polystyrene resin with syndiotactic structure to lower the surface resistance of molded products and impart conductivity, high heat resistance, high fluidity and relatively low temperature As a result, it has been concluded that high productivity can be obtained at the time of molding by the resin composition for molding an IC tray which suppresses generation of gas at the time of molding and has low mold contamination.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // (C08L 71/12 25:04 21:00 23:00)

Claims (6)

[Claims] (1) The weight ratio of (a) polyphenylene ether to polystyrene having a syndiotactic structure is 99.
100 parts by weight of a mixture having an oil absorption of at least 70 ml / 100 g or a volume resistivity of 10E0 Ω · c.
5 to 35 parts by weight of at least one selected from carbon fibers having a molecular weight of m or less; and (c) 0 to 30 parts by weight of polystyrene having no syndiotactic structure;
(D) 0 to 50 parts by weight of rubber-like substance, (e) 0 to 20 parts by weight of polyolefin resin, (f) non-conductive inorganic filler 0
A resin composition for molding an IC tray, comprising from 30 to 30 parts by weight. 2. The resin composition according to claim 1, wherein the intrinsic viscosity of the component (a) polyphenylene ether is 0.3 to 0.75 dl / g. 3. The resin composition according to claim 1, wherein the component (c) polystyrene having no syndiotactic structure is a styrene homopolymer and / or a rubber-reinforced polystyrene. 4. The resin composition according to claim 1, wherein the component (e) polyolefin resin is a low density polyethylene or a linear low density polyethylene. 5. The resin composition according to claim 1, wherein the component (f) the non-conductive inorganic filler is at least one non-conductive inorganic filler selected from talc and mica. 6. An IC tray molded article molded from the resin composition according to any one of claims 1 to 5.